Image artifacts can occur in CT images as a result of different effects. One of these effects is attributable to so-called beam hardening, which is caused by the energy-dependent attenuation of x-ray beams. Beam hardening occurs in CT scanners, because their x-ray tubes emit no monoenergetic x-rays but a broader x-ray spectrum. With the increasing thickness of the objects being irradiated, the low-energy portions of this x-ray spectrum are more strongly absorbed than the high-energy parts. A higher proportion of hard, high-energy radiation thus reaches the detector and dark zones arise in the image. Metallic implants too result in beam hardening. Excessively strong image artifacts may, for example, occur in the form of light and dark stripes in the vicinity of the metal.